In a heterogeneous network of hybrid deployment of a macro cell and a micro cell, for example, in a scenario of dual frequency-dual cell (DF-DC), dual frequency-3 cell (DF-3C) or dual frequency-4 cell (DF-4C) deployment, transmit powers of the macro cell and the micro cell on a primary carrier are usually unequal, resulting in that an uplink balance and a downlink balance of user equipment (UE) cannot be aligned. Herein, the uplink balance is a location of the UE when signals of the UE that are received by the macro cell and the micro cell have same signal strength, and the downlink balance is a location of the UE when signals of the macro cell and the micro cell that are received by the UE have same signal strength.
As shown in FIG. 1, in the foregoing scenario of hybrid deployment of a macro cell and a micro cell, for a primary carrier F1, a transmit power of the macro cell is 43 db, and a transmit power of the micro cell is 30 db. In the foregoing, what is below MF1 represents coverage of the macro cell on the carrier F1, what is below PF1 represents coverage of the micro cell on a carrier F2. An intersection point of MF1 and PF1 is a downlink balance of the UE on the carrier F1. For the secondary carrier F2, transmit powers of the macro cell and the micro cell are both 30 db. In the foregoing, what is below MF2 represents coverage of the macro cell on the carrier F2, what is below PF2 represents coverage of the micro cell on the carrier F2. An intersection point of MF2 and PF2 is a downlink balance of the UE on the carrier F2. Because on F2, the transmit powers of the macro cell and the micro cell are equal, the downlink balance and an uplink balance of the UE on the carrier F2 may be considered to be at a same location.
In the foregoing scenario of deployment, for the primary carrier F1, when the UE moves from the uplink balance to the micro cell, a downlink of the micro cell does not meet a 1A event triggering condition, the micro cell cannot be added to an active set of the UE, and an uplink transmit power of the UE cannot be controlled. Even if a cell individual offset (CIO) is extended to enable the UE to add the micro cell to the active set, the UE still cannot receive a power control command of the micro cell. Therefore, the micro cell is subject to strong uplink interference from the UE, and an uplink capacity of the micro cell is reduced. In addition, after uplink decoupling is performed, an uplink serving cell and a downlink serving cell of the UE are different cells. For example, downlink transmission takes place at the macro cell, and uplink reception takes place at the micro cell. In this case, the UE cannot receive data of a control channel such as an E-HICH of the micro cell. For example, after sending uplink data to the micro cell, the UE cannot receive feedback information returned by the micro cell. In this way, the UE may continuously perform data retransmission, and as a result, a service of the UE cannot work normally.
In conclusion, when UE is not within primary carrier signal coverage of a micro cell, the micro cell cannot control an uplink transmission action of the UE on a primary carrier.